A magnetic recording medium such as a magnetic tape is generally prepared by coating a magnetic paint comprising a magnetic powder and a binder resin over a support and then by drying the resulting coated support.
In recent years, for the purpose of improving the characteristics of a magnetic recording medium, it has been known to divide a magnetic layer into a plurality of layers and to contain a ferromagnetic metal powder in the outermost layer thereof and Co-.gamma.-FeOx in the layers other than the outermost layer thereof. [Refer to Japanese Patent Publication Open to Public Inspection (hereinafter referred to as JP OPI Publication) No. 64-19524/1986.]
When containing Co-.gamma.-FeOx in the layers other than the outermost layer as mentioned above, the RF output and lumi S/N thereof are equivalent to those of a magnetic layer comprising only a single layer containing ferromagnetic metal powder and the chroma output and chroma S/N thereof are further improved, as compared the above-mentioned two kinds of layers to each other, because Co-.gamma.-FeOx is normally lower in Hc than that of ferromagnetic metal powder. In addition to the above, Co-.gamma.-FeOx is more inexpensive than ferromagnetic metal powder, so that the production cost thereof may also be saved.
There is also a short-wave recording tendency in a recording system in which ferromagnetic metal powder is used, such as the recently developed Hi-Fi 8 mm video systems. Accordingly, in the ferromagnetic metal powder which is applicable to the outermost layer and contributable to a short-wave recording operation, it has become popular to use those having a substantially shorter average major axis length such as 0.25 .mu.m (i.e., 250 nm) as seen in JP OPI Publication No. 64-19524/1989.
However, even in the technique disclosed in the above-given JP OPI Publication No. 64-19524/1989, the resulting electromagnetic conversion characteristics including, particularly, the RF output and lumi S/N have not been satisfactory.